Carbon nanotube sensor can detect SARS-CoV-2
A team of chemical engineers at the Massachusetts Institute of Technology (MIT) has developed a new sensor for SARS-CoV-2, the virus causing Covid-19, using nanotechnology and a kind of polymer that can recognise virus proteins in the sample.
In a study published in Analytical Chemistry, the researchers report that the test takes only five minutes to complete and has a sensitivity to low concentrations of the virus similar to currently used antigen tests. Moreover, it presents two key advantages: the results can be given immediately without the need to send the sample for analysis in a lab, and the test can detect viral proteins in saliva, so it does not require an uncomfortable nasal swab.
The nanotechnology is based on carbon nanotubes. These are tubular structures with diameter a million times smaller than a human hair, and act as a sensor in the new testing technology. When you shine laser light on them, they fluoresce. Attached to these nanotubes are special polymers which are engineered by the MIT team to latch onto the virus proteins. When the viral proteins bind to this nanotube-polymer aggregate, it emits a different colour of light revealing the presence of the virus.
“The slow development of rapid testing in the Covid pandemic has cost millions to our economy,” says Prof Michael Strano, senior author in the study. “Our test has the potential to be used at airports to screen anyone coming off an aeroplane. The method we used can be applied to new pathogens, so we can be ready for future potential pandemics.”
According to the researchers, it took only 10 days to develop a reliable test from the moment they were supplied with the coronavirus antigens. In contrast, current testing methods, including the PCR molecular test and the lateral flow antigen test, took a long time to develop. The PCR test detects the genetic material of the virus, so we must first map the virus genome before a test can be developed. The antigen test, also known as the lateral flow test, requires the development of antibodies that can recognise the virus proteins, which is a time-consuming process.
The key component of the technology are the polymers that perform the molecular recognition. “A lot of viruses have the same n-protein, and we can engineer polymers to be exquisitely selective,” says Strano. The n-protein, or nucleocapsid protein, is the most abundant protein in coronavirus and is often used as a marker in diagnostic assays. “Every virus contains instructions to make its own biomolecules, which are like complex soft asteroids, and it’s possible to find something that latches onto features of these biomolecules”.
According to Strano, the materials used in the test are readily available and production is potentially scalable. At present, the researchers have a working prototype in their lab with a fibre optic tip that can detect fluorescence changes of the sample in real time. The hope is that technologies like this can be developed so we can be better prepared for new viruses that arise.